Modulation of Social Influence by Methylphenidate

Abstract

The ability to infer value from the reactions of other people is a common and essential ability with a poorly understood neurobiology. Commonly, social learning matches one's values and behavior to what is perceived as normal for one's social group. This is known as conformity. Conformity of value correlates with neural activity shared by cognitions that depend on optimum catecholamine levels, but catecholamine involvement in conformity has not been tested empirically. Methylphenidate (MPH) is an indirect dopamine and noradrenalin agonist, commonly used for the treatment of attention-deficit hyperactivity disorder for which it reduces undesirable behavior as evaluated by peers and authority figures, indicative of increased conformity. We hypothesized that MPH might increase conformity of value. In all, 38 healthy adult females received either a single oral 20 mg dose of MPH or placebo (PL). Each subject rated 153 faces for trustworthiness followed immediately by the face's mean rating from a group of peers. After 30 min and a 2-back continuousperformance working-memory task, subjects were unexpectedly asked to rate all the faces again. Both the groups tended to change their ratings towards the social norm. The MPH group exhibited twice the conformity effect of the PL group following moderate social conflict, but this did not occur following large conflicts. This suggests that MPH might enhance signals that would otherwise be too weak to evoke conformity. MPH did not affect 2-back performance. We provide a new working hypothesis of a neurocognitive mechanism by which MPH reduces socially disruptive behavior and provides novel evidence of catecholamine mediation of social learning.

Investigating the Genetic Basis of Social Conformity: The Role of the Dopamine Receptor 3 <b><i>(DRD3)</i></b> Gene

“…Previous research has demonstrated that enhancement of dopamine responses by direct administration of a dopamine and noradrenalin agonist (methylphenidate) facilitates the conformity effect [10]. The present study extended this finding by demonstrating that DRD3 , an important player within the dopaminergic system, is associated with individual differences in conforming behavior.…”

“…The increased reward-related dopamine activity is assumed to reflect the amplification of phasic dopamine responses to appetitive stimuli [22]. Methylphenidate, a drug that amplifies the dopamine response to appetitive stimuli [43], has been shown to increase conforming behavior after moderate social conflict [10]. The authors suggested that the enhanced dopamine response increases the magnitude of the incentive salience of agreeing with others [10].…”

“…These studies collectively suggest a role of dopaminergic neurotransmission in social conformity. Indeed, a recent work found that enhancement of dopamine responses via direct administration of a dopamine and noradrenalin agonist promotes conformity to group opinion [10]. Thus, it is possible that a receptor with the ability to regulate dopamine responses could modulate individuals' conforming behavior, which is related to social and reinforcement learning (see Discussion).…”

“…Given the role of Ser9Gly in reward-related dopamine responses [22] and the role of dopamine responses in social conformity [3,7,10], it is possible that the Ser9Gly polymorphism is related to social conformity, with the Gly allele being associated with increased conforming behavior. In the present study, 152 participants were genotyped for the Ser9Gly polymorphism and tested with a facial-attractiveness rating task [3].…”

“…Participants in this task are asked to rate the attractiveness of faces twice; in between those two ratings, the others' ratings are conveyed to the participants. It has been shown that participants' second ratings are highly susceptible to the group's ratings, with their ratings getting closer to the group's ratings [3,10]. This task can precisely quantify the degree of social conformity, providing a much more sensitive measurement of conformity than other coarse measurements (e.g.…”